I show that among women likely to use welfare, movers move to higher-benefit states. I also find that the probability likely welfare users will move at all is lower in higher-benefit states. This effect is concentrated early in the life cycle, as theory predicts. I construct a theoretical framework to measure the impact of welfare migration on optimal state benefits. Simulation results suggest little impact in higher-benefit states, but possibly a more substantial impact in other states. Finally, evidence suggests little reason for concern (due to welfare migration) in using cross-state variation in welfare generosity to identify incentive effects of the welfare system on other outcome variables.